NVIDIA GeForce 6800 Ultra (NV40) Review
The GeForce 6800 Ultra reference card is based on the native AGP
native design where the PCI-E version, NV42 will arrive in later half of this
year. The GeForce 6800 Ultra may look quite massive due to the cooler but it is
of still of the same length as the retail Inno3D GeForce FX 5950 Ultra and it is
rather light too. The GeForce 6800 Ultra is clocked at 400Mhz for the core and
550Mhz for the 256MB onboard DDR3 memory at a suggested price of US$ 499.
On the back of the GeForce 6800 Ultra, there are no memory
modules since all the 8 GDDR3 memory modules of 256MB are located at the front
of the card. Therefore, it will allows for another 256MB GDDR3 to be packed into
this card where NVIDIA said that the 512MB card will be available this summer.
However, judging from the large number of SMD capacitors packed onto the back of
the card currently, adding another 256MB GDDR3 to the current PCB design is
quite a challenge.
As you can see, the NV40 die is large since it is based on the
mature 130nm FSG process technology from IBM and contains 222M transistors. Bulk
of the die size/transistors are allocated to the shader pipelines and probably
the on-chip video processor as well. On a 300mm wafer, about 190 NV40 cores can
be made only therefore we can expect a rather moderate yield. This NV40 is
manufactured in Korea at Week 12 of 2004 with A1 stepping and has relatively low
core frequency of 400Mhz, which is some 75Mhz lower than that of the NV38.
NVIDIA chooses to use the Samsung K4J55323QF-GC20 GDDR3 memory
in 144 Ball FBGA package located at the front the card with 8Mx32 array. The
K4J55323QF-GC20 has an effective data rate of 1000Mbps/pin which is under
specifications since GeForce 6800 Ultra memory is clocked at 1100Mhz. This is
kind of a surprise that NVIDIA overclocked their memories for the GeForce 6800
Ultra. Samsung offers higher speed GDDR3 memories like GC16, GC14 and GC12 which
have an effective data rate of 1200Mbps/pin, 1400Mbps/pin and 1600Mbps/pin
respectively. It would certainly be interesting to see GeForce 6800 Ultra with
memory clock at 1400Mhz or 1600Mhz although the price will definitely be higher
and the performance gain wouldn’t be substantial.
The GeForce 6800 Ultra card has 2 Dual-Link DVI interfaces
powered by two Silicon Image 178CT64 TMDS chips located at the front and back of
the card as well as one TV-out. Certainly, card manufacturers have the choice to
ship their cards with 1 DVI-output or 2 DVI-out like the reference card but it
is preferably to have two for this high end card.